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WILLIAM COLBORNE CAMBRIDGE, OF BRISTOL, GREAT BRITAIN, ASSIGNOR TO HELSELF ANI) J. T. GRIFFIN, OF NEW YORK CITY.

Letters Patent No. 83,689, datati Noveafnbco` 3,' 1868.

IMPROVEMENT IN G'RATE-BARS FOR FURNACES.

The Schedule referred to in these Letters Patent and.making part of thesame- To all whom itma/y concern:

Be it known that l1, WILLIAM ,GOLBORNE OAM- BRIDGE, of Bristol, in theKingdom of Great Britain, engineer', have invented a new and usefulImprovement in Furnace-Grate Bars; and I do hereby declare that thefollowing is a\full and exact description thereof, reference being hadto the accompanying drawing, in which- Figure 1 is a perspective Viewyof the top tion of one of my improved bars;

Figure 2 is a transverse section 5 and Figure 3, a perspective view ofthe under side of the same.

Like letters designate corresponding parts in all of the figures.

The -nature, of my invention consists in constructing grate-bars withvertical lateral ribs, in combination with a depressed central web,pierced with obliquely-trans verseopenings or air-passages, ashereinafter set forth;

As represented in the drawings, A A constitute the vertical ribs orsupporting-portions of each bar, and

of a por- B B, the central web uniting them, which is pierced by thecells or openings o o.

The ribs standing above the surface of the web, at a.' a, keep the fuel,to a great extent, from resting on the latter, thereby leaving aspacefor the circulation of air above the surface of the ribs B, which notonly keeps the metal from becoming overheated, but, by diffusing airmore generally through the fuel, produces more perfect combustion. v

Ordinarily the grate or fire-bar presents so large a surface to the fuelwhich it supports, as to materially intercept the entrance of air,rendering the combustion slow and imperfect at the points in contactwith the bar. f This defect results from the considerable size requiredto insure the requisite strength under the' weight of the fuel when themetal is weakened by the My improved construction obviates this, bymaking the bar very strong vertically, in consequence of the great depthof the ribs Aand by avoiding vthe overheating of the metal, by the largeamount of surface exposed to the cold air, and the very small surfacewhich is in direct contact with the fuel, it being only the top, a, ofthe libs, and from this construction also result the advantages ofadmitting air to the fuel, through nearly the whole of the spaceoccupied by the bar, and of preventing the fuel or cinders fromcompacting upon the top of the bar, while the bars are both light andstrong, and possess increased durability.

I do, not confine myself to any particular size or pro;

portion of the ribs or openings, only that they are fomned `between ribsVraised vertically at each side of the bar, the said openings taperingupwards, leaving, at the top, portions of metal between ysuch openings,of greater thickness than at the bottom of each of said bars, and theseopenings may extend obliquely across Afrom one4 side of the bar to theother,V or they may be turned off -at an angle, as shown.` The lengthand strength of the said bars may bewaried according to circumstances.`

The ribs standing above the web at the sides, may be of any height andthickness that may be needful, and very suitable dimensions are half aninch rise above the surface of the web, and a thickness of half an inc hon the level of the top of the web, b evelled off to the top ofthe rib,to facilitate lifting and moulding. These vsides keep the fuel morehollow orlocse, and cause the air to act more evenly and eii'ectuallythrough the fire, thus producing more heat with less fuel.

What I claim as my invention, and desire to secure by Letters Patent,is-

A tire-bar, constructed with vertical side ribs A A, having raisedledges c a, in combination with the depressed web B and oblique openingc, substantially as and for the purposes set forth.

In witness where0f, I have hereunto signed my name` in the presence oftwo subscribing witnesses.

NVILLIAM COLBORNE CAMBRIDGE.

Witnesses:

STC. EAs'rMAN, JOHN G. DoDDs.

